The research is concerned with the role of multiple gene loci which determine the structures of organ specific enzymes with very similar but not identical enzymic properties. In particular the biochemical genetics of the aklaline phosphatases will be studied because previous work indicates that this set of enzymes provide a good model system pertaining to this not uncommon phenomenon. The biochemical, immunological and genetic characteristics of these enzymes in man and also other mammalian species will be examined in order to determine the number of gene loci involved, the differences between their products, their organ specificity and their degree of allelic variation in different species. Aberrant expression of alkaline phosphatase loci in cultured cell lines derived from maligant tumors will also be studied.